Controlling a cheap TTL RGB module.

[FishBulb32]

I’ve been reading up on ttl and am aware it’s 5v so I’ll be sure to power it correctly.

Right, I’m not having much luck. The power supply that it was working with is now no longer powering it. It was working fine for about 10 mins of use. Moving it around etc changing the colours. The supply is fine, still reading 12v. Starting to think I may have a dodgy unit? Any ideas?


EDIT:

Scratch that! Seems the polarity of the input is backwards. I guess I must have flipped it by mistake when testing the second PSU. When I went to make secure connections I went back to making it all look correct and of cause it stopped working again. Finally figured it out anyway. Working fine now and I know why.

It’s really nice overall. Each colour is great on its own and the mixing is really fun. The alignment isn’t perfect at a distance but I’m happy with it.

Now to make it portable and get a controller put together for it.

 

[RedCowboy]

The TTL is transistor to transistor logic and controls via pulse width the duration of each cycle that the laser is " on " and when it's " on " it's " on " at full power but only for a percentage of the cycle, so if you are modulating at 10k and 30% the laser will pulse on-off 10,000 times a second and will be on for 30% of each pulse and off for 70% of each pulse, adjust it up to 80% and your laser is on for 80% of each pulse and off for 20% of each pulse.
Note: If your driver is analog it will average out the TTL and adjust current to your laser as it's designed, but your TTL control works the same.

The 5v is just the trigger voltage, actually it turns on at 3.5v and above and off below 0.8v so your PWM generator should put out the 5v when you power it by it's spec, however many of the Chinese PWM generators take 3 -30v and in the specs say ( Output amplitude: PWM amplitude equal to the supply voltage ) so in that case which is likely what you have you want to supply it with 5v but it won't need much current because it's only powering a transistor, your laser is powered by it's own supply.

Also your laser driver will have a specified response range of something like 0-30KHZ so if your PWM generator can output 1HZ to 150KHZ then set it within your laser drivers range such as 10K, this will not effect the brightness of the laser.

 

[FishBulb32]

Thanks for the info. Very well put. Really feel like I’m learning a lot here.

I’ll have a play with the PWM the weekend and then hopefully look into building into something that resembles a portable unit.

 

[paul1598419]

Paul, this brings up a little bit off the cuff question..
I'm using a Wall Wart 12V at 1.88A to run the 505 mini labby I got a couple months ago..
Silly question, if I were to run a lower amp wall wart would there be laser power difference?

No, the driver will only pull as much current as it needs to power the laser. You can use any 12 volt supply that will supply enough current to operate it. You could use a 12 volt 20 amp supply as the driver won't pull that much current. Only what it needs to operate. You do have to have a supply that will give enough current, though.

 

[ArcticDude]

It’s arrived. Very fast shipping!

I was under the impression that just giving it 12v would give me a white laser. Is that not the case with this unit? I’ve got nothing once giving it 12v.

https://imgur.com/1B0Q0PO

EDIT:

Its working fine. I tried a different power supply with lower amps and it’s running great. Am able to turn all the colours on and off.

I’ve got a 3 channel PWM controller turning up in a day or two to play with. And hopefully be able to get Big Clive’s controller working with it too.

I’m gonna go back to testing it out. I’ll try and get some photos and do a little review when I get time.

PM sent..

 

[FishBulb32]

Massive thanks to ArcticDude for his help today. Managed to mod Big Clive’s controller and got it working with this unit. Had no idea it would be so easy.

I’ve been playing with it this evening and am having so much fun. For less than £40 this thing is amazing value.

I’ll do my best to do a write up of both the unit and my time with it. But for now here’s a little gif of how I’ve spent my evening...

https://imgur.com/pc1RL9O

https://imgur.com/QsATVvx

 

[ArcticDude]

Yes, that El Cheapo RGB unit is fun to play with..
If you're DIY oriented person I can warmly recommend to build HDD XY scanner from old HDD drives.

Cheers,
Tero

 

[FishBulb32]

I’ve got a few options now for where to go next with it. I’ve come across HDD scanners over the past week and as I work in computer repairs, I have an endless supply of dead HDDs. So that’s one option. Or just build a line generator and do the liquid sky thing. But first I need some sort of case to protect it.

If I decide to do it; Any recommendations on how to power this correctly with 18650 batteries? Again, getting hold of those is no problem for me.

 

[ArcticDude]

I’ve got a few options now for where to go next with it. I’ve come across HDD scanners over the past week and as I work in computer repairs, I have an endless supply of dead HDDs. So that’s one option. Or just build a line generator and do the liquid sky thing. But first I need some sort of case to protect it.

If I decide to do it; Any recommendations on how to power this correctly with 18650 batteries? Again, getting hold of those is no problem for me.

I recommend to get a proper voltage regulator: Matek PDB or similar..
Input voltage can be 9V-18V and you get nice regulated 12V output for RGB unit & controller.
You can use Multirotor Li-Pos or 3 or 4x Li-Ions (18650 / 26550)

 

[FishBulb32]

I’ve been putting together a bit of a review for this, getting some photos too. Today I was going to build it into a small project box with some switches. Unfortunatly at some point the green laser has decided to only light up very dimly. The voltage at the green jack that goes out to the laser is reading just under 12v. Isn’t this too high? I can’t see anything that looks odd. This is with the unit on its own, not having the controller connected. Is this typical of a dead diode or something to do with the driver?

 

[ArcticDude]

I’ve been putting together a bit of a review for this, getting some photos too. Today I was going to build it into a small project box with some switches. Unfortunatly at some point the green laser has decided to only light up very dimly. The voltage at the green jack that goes out to the laser is reading just under 12v. Isn’t this too high? I can’t see anything that looks odd. This is with the unit on its own, not having the controller connected. Is this typical of a dead diode or something to do with the driver?

Sounds like you have toasted channel on driver board and probably dead green DPSS.. It shouldn't be that high +12V to green DPSS.
Can't say for sure..

 

[FishBulb32]

The green is a 505nm. I’m starting to think it’s toast, too. Just annoying that I’ve no idea what’s caused it.

 

[paul1598419]

That was my understanding too, that the green is a direct diode. These 505nm greens have a fairly high Vf, so it could have +12 into the driver section for that diode. I don't know what happened here, but unless you increased the current to the diode past its ability to keep the temperature reasonable, it shouldn't have LEDed the diode. But, it is possible that the diode is toast as this can happen without warning. Unfortunately, the only way to find out is to try to drive the diode independent of the driver and see if it is actually a diode failure.

 

[RedCowboy]

I’ve been putting together a bit of a review for this, getting some photos too. Today I was going to build it into a small project box with some switches. Unfortunatly at some point the green laser has decided to only light up very dimly. The voltage at the green jack that goes out to the laser is reading just under 12v. Isn’t this too high? I can’t see anything that looks odd. This is with the unit on its own, not having the controller connected. Is this typical of a dead diode or something to do with the driver?

It could be putting out 12v open and will be closer to 5-6 with the diode in the circuit, I would test the diode and put a load on the output and see if that 12v drops, but as it's driving a diode and not a driver at the diode it shouldn't be 12v while connected to a load.

 

[paul1598419]

It depends. Are you reading +12 volts across the diode or are you only reading the voltage to ground at one side of the diode? If it is +12 volts across the diode that is far too high.

 

[FishBulb32]

Thanks for the input guys.

It’s 12v across the diode while it’s all connected and running as a white laser.

Diving any further into diagnosing this is probably way out of my comfort zone. I’ll message laserlands and see what they say.

I may end up just writing the 505 off, not bothering with any fancy controll and just calling this a magenta laser to add to my collection. Knowing magenta is impossible with a single diode at least gives meaning to having one. Every cloud...

I guess I’ll have to revisit a portable RGB in the future.